A cooling apparatus of the above type operates in a socalled "dual phase" mode, in view of the fact that the coolant fluid, which is generally a mixture of water and antifreeze, is present in its two distinct phases, namely the liquid and vapour phases. Dual phase cooling must be distinguished from the conventional mode of cooling internal combustion engines in which the coolant fluid exists only in its liquid phase. In conventional cooling apparatus the coolant fluid in its liquid state is, after leaving the engine, cooled in a radiator which is equipped with a fan, after which it is passed back into the engine, flow of the liquid being obtained by forced convection under the action of a pump. In cooling apparatus operating in dual phase mode, the vapour is condensed in a condenser which is arranged in the same location as would be occupied by the cooling radiator in a conventional system.
Dual phase cooling systems for internal combustion engines are known per se. They include a coolant fluid inlet, into which the fluid is delivered in the form of a mixture of its vapour and liquid phases, a liquid coolant fluid outlet, a condenser interposed between the fluid inlet and the fluid outlet, a phase separator interposed between the fluid inlet and the condenser, a liquid reservoir or sump interposed between the condenser and the fluid outlet, and a liquid flow passage means connecting the phase separator and the liquid reservoir together. Such an apparatus will be referred to as a cooling apparatus of the kind specified.
It should be made clear that such dual phase cooling apparatuses are still in the experimental stage, and have not yet been fully developed for production. Production on an industrial basis is currently hindered by numerous practical difficulties. In particular, one of the disadvantages of such apparatuses lies in the fact that they call for a very large number of components, particularly a phase separator, a condenser, a liquid reservoir for acting as a sump, a circulating pump, and (where necessary) an expansion chamber.
Up to the present time, connecting all these various components together requires the use of a number of ducts or conduits of different diameters which have to be adapted as necessary to the flow of fluid in the vapour state or to flow of fluid in the liquid state, together with the appropriate connecting elements and pipe clips and the like. All this gives rise to a considerable danger of leakage of cooling fluid from the apparatus, both in the vapour and in the liquid state.
In addition, manufacture of such a cooling apparatus calls for complex assembly operations, and therefore makes them somewhat expensive, so that they are not at present a cost effective proposition for industrial production.